1. Field of the Invention
The present invention relates generally to spools, and more particularly to a web-spool for a cartridge or the like.
2. Description of the Prior Art
It is known in the minilab printer art to provide long rolls of photographic paper, and in the computer output microfilmer art to provide longe rolls of 16 mm or 105 mm photographic film, each in convenient daylight-loading cartridges. Those cartridges generally comprise a cylindrical core onto which the film or paper is wound to form a web-roll. The web-roll is enclosed within the cartridge and rotatably supported by sidewalls thereof. The cartridge is provided with a web exit slot having opposed surfaces to which a plush or foam material is applied to allow the web to be withdrawn from the cartridge while excluding light from the cartridge interior. Typically, an anti-clockspringing bar to prevent rotatikon of the core during shipment is installed through holes in a cartridge rim surrounding the core end, and through one of a plurality of aligned castellations on the core end.
As a need has developed for greater web widths and longer web lengths, a problem has arisen in which the web-roll within the cartridge dishes or telescopes axially as a result of shock and vibration during shipment of packaged cartridges. When a web-roll dishes or telescopes, portions of the faces of the web-roll may rub against the interior side surfaces of the cartridge, resulting in an unacceptably high web withdrawal force. A further problem is breakage of the cartridge, core, or anti-clockspringing bar as a result of the high rotational, inertial forces caused by the longer, wider, and heavier web-rolls.
The aforementioned problems may be solved in part by attaching a pair of flanges to opposite ends of the cartridge core to constrain a roll wound on the core from dishing or telescoping into contact with the interior walls of the cartridge. With such a web-spool, the anti-clockspringing mechanism can be mounted on the cartridge, as shown in U.S. Pat. No. 4,802,633, to engage the periphery of the flange instead of the cartridge core.
Tape- or film-spools are also well known in the art, as indicated in U.S. Pat. No. 3,438,592 and the above-mentioned U.S. Pat. No. 4,802,633. The film spool comprises three distinct elements, namely, two flanges and a cylindrical core, which are rendered integral by assembly. In U.S. Pat. No. 3,438,592, the core has annular throats into which project circular sectors separated by core notches provided for passage of lugs on the flanges. One disadvantage of that type of film-spool is that is would be extremely difficult to accurately wind the film onto the core prior to mounting the flanges on the core. The slightest axial telescoping movement of the film as it is wound would make it extremely difficult, if not impossible, to attach the flanges onto the ends of the core. That problem is overcome in the present invention by providing radially outwardly extending tapered guide rings facing each other at the ends of the core for initially guiding the web onto the core and to provide clearance between the web edges and the flanges. The clearance accommodates web telescoping so that the flanges can be secured to the core ends without any interference of resistance from the wed edges resulting from any axial telescoping of the roll that occurs during winding.